The present invention pertains to heat exchangers for flowing fluid materials and, more particularly, to a modular heat exchanger construction in which the individual modules utilize easily demountable connectors to facilitate separate module replacement.
The prior art discloses the use of heat exchangers in which the tubular outer wall of the conduit containing the fluid flow is corrugated. Typically, each of the corrugations is provided with an interior baffle plate which blocks direct flow of the fluid through the conduit and causes the fluid to be diverted from a purely axial flow. The diversion of fluid flow by the baffle plate slows the flow through the conduit somewhat and enhances the heat exchanging contact between the fluid and the walls of the conduit, the surface area of which is substantially enhanced by the corrugated construction.
More conventional heat exchanger construction, particularly heat exchangers adapted for automotive use, utilize the so-called "tube and header" construction. In this type of heat exchanger, a core element including a series of generally parallel tubular conduits extends between and are attached at their opposite ends to inlet and outlet headers. The tubular conduits are also generally provided with attached heat conducting and dissipating fins which may be of either a flat plate or serpentine construction. The rigid joints between the fluid conduits and the headers are generally soldered or brazed and, as is well known in the art, are relatively weak. In fact, the soldered joints constitute the weakest points in a typical tube and header heat exchanger construction and are generally the first to fail under excessive loadings which may, for example, be caused by thermal expansion or shock loads. Thus, no significant axial elongation of a conventional heat exchanger module resulting in relative movement between the fluid conduits and the header or header plates can be tolerated.
Conventional automotive heat exchangers or radiators typically have an upper inlet header and a lower outlet header between which the core unit is mounted and all of which is enclosed in a generally rectangular supporting frame. This rigid mounting of a conventional tube and header core exposes it to joint failure as a result of thermal forces as well as shock loads. Heat exchangers utilizing a corrugated conduit construction might be manufactured to allow some axial strain under load which will avoid failure of the connecting joints. In either type of construction, it has always been desirable to provide a modular construction in which the entire heat exchanger unit may comprise a series of individual modules which can be separately replaced if damaged or destroyed. Such a modular construction would be particularly attractive in conventional tube and header heat exchanger constructions where serious damage to the core element usually requires replacement of the entire core.
U.S. Pat. No. 1,816,159 shows a corrugated conduit heat exchanger which may be mounted between a pair of oppositely disposed headers via axially bolted end plates. German Patent 577,743 and British Patent 114,821 disclose modular tube and header heat exchanger constructions in which the individual tubular modules are connected between the headers with threaded connectors. However, the threaded attachment of the connectors imposes an axial strain on the modules which might result in fracture of the soldered joints. French Patent No. 673,524 discloses modular heat exchanger elements, but the same are demountably detached to the outer faces of the headers, rather than between the headers as in conventional construction.